Because people take their time sipping hot beverages, it is desirous to retain the temperature of the beverage and preserve the beverage's integrity for as long as possible. Maintaining the temperature, especially of a beverage such as coffee or tea, has been a challenge. Various attempts have been made to maintain the temperature of a desired beverage or food in a vessel. For example, electrically heated hot plates for individual mugs or candles require an electrical outlet to sustain the heat or a wick to produce a fire source of heat.
The devices in the prior art suffer from certain drawbacks. Hot plate style devices require a constant flow of electricity and an electrical outlet needs to be proximate which is not always the case. Even battery-powered hot plates have similar issues—to maintain the temperature of the contents of the vessel, the plate must be kept “on” and becomes hot to the touch, resulting in possible burns for the user. Additional issues include a scalded taste for the contents, and a paper item may be accidentally laid on top of the hot plate or be ignited by proximity to the heating element, which might even include an open flame. Some powerful warmers cause evaporation over time and thereby cause the remaining contents to result in a gummy residue and the scalded taste. Forgetting to turn the warmer off can be problematic, dangerous and an unnecessary use of electricity. Someone may burn themselves on the hot plate. Specialized portable warmers and heaters are not truly portable due to requiring wall current or open flame.
In addition, other devices have been tried but have other limitations. Various devices, such as sleeves serve to insulate a hot beverage from a person's hand, but do not effectively maintain the temperature or retard the cooling of the beverage. Other devices, such as foam insulators, can be bulky or difficult to hold, or can cause the vessel to become unbalanced when held, so as to result in spills. Such spills from hot beverages can be dangerous.
Vacuum bottles and highly insulated containers are also available for the purpose of maintaining the warmth of a beverage as well. However, drawbacks exist with respect to vacuum bottles and highly insulated containers. First, the bottle serves as the vessel itself and not as an insulator for a container. These bottles do now serve to “wrap” another vessel. As such, they usually require a lid that must be placed back onto the container after each use. Further, the beverage must typically be poured into another container for use, thereby eliminating the utility for more solid foods. Typically, plastic cups are included for pouring the hot beverage into. To some tastes, the plastic cups typically alter the taste of the beverage. Some thermal vacuum bottles have a rubber gasket within the lid that decays, comes apart and may fall into the beverage. The rubber gasket may acquire a bacteria residue which can be odorous and difficult to clean. Typically, if the rubber gasket fails, the entire device needs to be replaced. Some of the insulated containers that contain heating properties have ingredients that are chemical based and render vaporization problems. Further, because the same vessel is always used, and the contents are changed from one use to the next, such as from soup to coffee, an unacceptable after taste may remain behind. Further, these bottles may be difficult to clean.